1. Technical Field
This invention relates generally to substrate transfer and handling apparatus and more particularly to improvements to a mechanism for releasably transferring a substrate to and from a processing machine.
2. Description of the Prior Art
With the existence of high throughput process equipment, automatic substrate handling is most essential. The need for higher yield in the manufacture of semiconductor devices has driven the development and use of more highly automated semiconductor substrate handling apparatus. Furthermore, the need to reduce particulate levels in the processing areas have demanded the use of controlled substrate containment in which substrate transfer occurs. Traditional tooling front-ends, in which substrate transfer handling occurs, have historically involved labor-and time-intensive integration of multiple components-atmospheric wafer-handling robotics, load-ports, wafer identification and tracking readers, mini-environments, control software—to form an ever increasing complex of front-end tooling. Chip manufacturers are seeking less complicated, highly reliable and more serviceable equipment solutions. This is due to the relatively high cost of down time in semiconductor facilities.
Prior art provides a substrate transfer apparatus that is simple, which reduces particulate generation, and is somewhat reliable. The substrate-transporting robot must be exacting in its handling of the fragile substrate. Horizontal positioning is difficult to control as distances increase particularly with increasing substrate sizes and chamber dimensions. Shifting of a substrate while being supported on a transfer paddle causes a substrate to be out of its expected position on the paddle. Shifting occurs during movement if a friction pad is missing on the top surface of a paddle. This problem can generate particulate contaminates as well as breakage because of interference with stationary members. The prior art handler does not provide anticipated reliability during the transfer operation.